The Radial Nerve
The radial nerve is a nerve that supplies muscles
responsible for extension of the elbow, outward
movement of the forearm, and extension of the
wrist and fingers. It runs down the back of the arm,
travelling to the front of the elbow, and then down
the forearm.
What is Radial Nerve Palsy?
Radial nerve palsy occurs when there is injury or
compression of the radial nerve, affecting its
function. This may present with varying degrees of
weakness of the abovementioned muscles,
depending on the level of injury to the radial nerve.
Causes
The radial nerve may be injured by:
- Direct trauma to the arm or forearm;
- Fractures of the humeral shaft (the arm bone);
- External pressure/compression (e.g. tumours);
- From prolonged pressure - such as lying on the
arm for extended periods.
Symptoms
Symptoms of radial nerve palsy may include:
- Loss of ability to extend the digits and wrist
- Loss of ability to rotate the forearm outwards
- Loss of elbow extension
These are affected to varying degrees depending
on the level of the nerve injury.
Patients usually have a "dropped" appearance of
the wrist and fingers. There may also be numbness
at the back of the hand.
Diagnosis
The diagnosis of radial nerve palsy and the level
of injury is determined based on the extent of
weakness and numbness.
Additional tests such as X-rays, electrodiagnostic
studies, nerve ultrasound or even Magnetic
Resonance Imaging (MRI), may be needed,
depending on the underlying cause for the radial
nerve palsy.
Treatment
Treatment for radial nerve palsy depends on the
underlying cause.
- If the nerve is cut, surgical repair or grafting is
recommended.
- If the radial nerve palsy is due to external
compression, surgical decompression may be
required.
- Other procedures (such as tendon transfer
surgery) may be recommended, depending on
the timing from injury and chance of recovery.
After the operation, supportive or functional
splints are provided to maintain the posture of
the wrist and fingers, while the nerve recovers.
Therapy is needed to maintain joint mobility and
slowly strengthen the involved muscles. Recovery
may take up to 6 months or beyond.
In most cases, the radial nerve palsy is only
expected to be temporary. Progressive signs of
nerve recovery may be observed over a period of
3 - 6 months. Interval splinting and therapy 1s
recommended while awaiting recovery.
